Master of Shrouds Summon Undead caster level@starwed if a SLA does not replicate a specific spell, a spell level equivalent should be stated in its description, for that very purpose. d20srd entry for SLAs implicitly suggests that (see save DC calculation).

D&D 3.5 mounted movement in battleMounted Combat feat (taken by a character) already does what you describe - allows you to get your mount out of the harm's way. Still yours is not an unreasonable houserule - the benefit in question is so minor it would hardly affect anything.